Shale oil recovery process



May 6, 1969 M. U. ZIMMERMAN,

SHALE OIL RECOVERY PROCESS Original Filed Oct. 31.

INVENTOR. MARLIN U. ZIM MERMA N, JR.

l IIBY United States Patent 3,442,789 SHALE OIL RECOVERY PROCESS MarlinU. Zimmerman, Jr., Shaker Heights, Ohio, as-

signor, by mesne assignments, to Technikoil, Inc., Cleveland, Ohio, acorporation of Ohio Continuation of application Ser. No. 320,451, Oct.31, 1963. This application Oct. 26, 1966, Ser. No. 589,756 Int. Cl. Cb53/06; C10g 9/28 US. Cl. 208-8 9 Claims ABSTRACT OF THE DISCLOSURE Thisapplication is a continuation of Ser. No. 320,451, filed Oct. 31, 1963,now abandoned.

The present invention relates to the distillation of oilbearing mineralssuch as oil shale, oil sands, tar sands, coal, lignite, peat and thelike. More particularly, the present invention pertains to an improvedprocess for distilling oil shale or the like wherein at least a portionof the heat required for distillation is supplied by direct heatexchange of the fresh shale with an extraneous gaseous heat carrier.

It is known that certain types of naturally occurring oil-bearingminerals such as oil shale and bitumen, contain materials which may beconverted by a pyrolytic treatment into hydrocarbon oils in commerciallyfeasible yields.

In general, oil shale retorting plants must have facilities for handlingcrushed raw shale, heating it to retorting temperatures, discharging thespent shale and collecting the retort products.

Oil shale has been defined by the'American Society for Testing Materials(D288-47) as a compact rock of sedimentary origin, with ash content ofmore than 33% and containing organic matter that yields oil whendestructively distilled but not appreciably when extracted with theordinary solvents for petroleum.

An object of this invention is to effect the distillation of oil shaleand the like at relatively low temperatures; with a rapid transfer ofthe distilling heat to the material being distilled, and without anynecessity for employing the expensive heating surfaces heretoforerequired because of the slow and inefficient heat transfer of prior lowtemperature distillation practice.

The present invention, in some of its aspects represents an improvementover the Swedish Aspeco shale oil distillation process in that thepreferred embodiment of it employs the so-called ball-furnace type ofheat exchanger although it differs from the Aspeco process, forinstance, in that it eliminates the necessity for the circulation of hotballs and attendant equipment. The heat transfer medium in the presentprocess is a gas, and preferably a light hydrocarbon gaseous product ofthe distillation step. The recycle hydrocarbon stream is used totransfer heat required for the release of oil from the oil shale.

The present invention makes effective use of the highly efficient heattransfer from hot gases to cooler solids. At the same time it avoids thedisadvantage of mixing combustion products with the recovered oil andgases.

The invention mainly resides in a method of heating granular orpulverulent materials by admixing into said ICC material loose solidbodies and a hot gas, said solid bodies being preferably attritionresistant and generally of larger piece-size than that of said material,and separating said material from said solid bodies after the solidmaterial has been heat treated in a rotary furnace in cofiow orcounterfiow.

Broadly, the invention involves feeding crushed shale through a systemcomprising several superimposed sections. The cold raw shale in lumpform is preferably preheated. The preheated raw shale then passes into aretorting or pyrolysis section where it is contacted with hot gases.Finally, if it is so desired, the spent shale with most of thehydrocarbons removed, but containing carbonaceous deposits, is passed tothe combustion section where a combustion supporting gas, such as air oroxygen, is contacted with the carbonaceous spent shale to supply heatfor carrying out the process.

The pyrolysis vessel or kiln in the instant process is preferably a ballmill equipped with a set of loose solid bodies, such as steel balls, aninlet for fresh shale, an inlet for the hot recycle gas heat-transfermedium and outlets for the spent shale and the cooled recycle gas andsome means for retaining the balls in the ball mill .apparatus. It isnot necessary that the pyrolysis vessel contain the permanent solidbodies, but it is preferred that the solid bodies be present becausethey reduce the tendency of the shale to bridge or agglomerate duringthe pyrolysis and they aid in the transfer of heat from the hot gases tothe oil shale.

The term pyrolysis as referred to herein, denotes the actual conversionof kerogen or organic matter in the oil shale to oil or oil vapors andgases. Included within this term pyrolysis is the process of separationof oil from other oil-bearing materials, such as bituminous sand (e.g.,tar sands, oil sands). The pyrolyzed carbon-containing residue isreferred to hereinafter as shale coke and the combusted shale coke isreferred to hereinafter as shale ash.

The accompanying drawing forms a part of this specification, and showsfor purposes of exemplification, one form of apparatus for carrying'outthe improved low temperature distillation of the present inventionwithout limiting the invention specifically to such illustrativeinstance.

In the drawing the cold oil-bearing shale 1 enters the preheater 2wherein the shale is preheated either by exchanger or by direct contact.The preheated shale 3 from the preheater next enters the pyrolysis drum4 wherein pyrolysis takes place. The pyrolysis drum is rotatably mountedand rotatably supported, for example, on rollers and a base andpreferably is somewhat tilted on its axis of rotation to allow thegravity flow of the shale from one end of the pyrolysis drum to theother and may contain solid bodies such as steel balls. The pyrolysisdrum may also be fixed and equipped with a rotatable screw and externalmeans for recycling the balls from the top to the bottom of the drum asdescribed and claimed in the copending US. patent application of HowardP. West, Ser. No. 320,450, filed Oct. 31,1963. The spent shale or shalecoke which still contains carbonaceous materials leaves the pyrolysisdrum and enters a hopper 5 equipped with a cyclone 6 for removal offinely entrained solids. The hot shale coke enters the coke burner 7where the mixture of shale coke and air (or any oxygen-containing gascapable of supporting combustion) from the air blower 8 is combusted toform hot gases which are used in heating the recycle gas in the heater9. The shale ash is removed from the bottom of the coke burner as itforms. The pyrolysis vapors 10 from the pyrolysis drum 4 pass overheadfrom the hopper 5 and cyclone 6 which removes entrained solid fines toan efiicient fractionater 11 from which the shale gas oil is taken offat 12 and the residual oil which goes to fuel or further processing istaken off at the bottom of the fractionater 13. The overhead gases fromthe fractionater 14 are cooled with air 15 by indirect heat exchange,water, etc., partially condensed 16 and compressed 17 and passed to anabsorber-stripper 18 where the condensed hydrocarbon is removed at thebottom 19 and the gas is removed overhead 20 and may be recirculated.The condensed hydrocarbon is then passed to a debutanizer 21 from whichbutane and similar hydrocarbons are removed and circulated 22 to theheater 9 where they are heated and converted to vapor having atemperature of from about 800 to 1200 F. and the heated vapors 23 arethen passed into the pyrolysis drum 4 to supply the heat for thepyrolysis. If the gas is recirculated from 20 it is brought into thesystem at 24.

The solid bodies useful in the pyrolysis drum in the preferred form ofthe present invention are preferably in the form of balls, pebbles orshot of suitable size and specific gravity. These solid bodies can becomposed of cemented shale ash or inexpensive metals such as iron,steel, aluminum, high melting lead alloys and the like as well asrefractory materials and particularly ceramic materials which haverelatively high heat capacities and are not subject to oxidation orreduction. The particle sizes of these solid bodies or balls can varyfrom about 50 mesh to about 1 inch in diameter. It is usually necessarythat the balls be larger than the crushed shale coke so that the shalecoke can be separated from the balls as it leaves the pyrolysis drum.

Most oil shales are preferably preheated to a temperature of betweenapproximately 400 and 600 F. in the preheater. At temperatures above 600F., pyrolysis of the oil shale commences with consequent loss of oilvapors and gases. Also at temperatures higher than about 600 F., the oilshale commences to become sticky or gummy and it is undesirable for thiscondition to exist in the preheating zone.

The hydrocarbon oil recovered from the shale is converted to a volatileproduct which can be treated according to the customary oil refiningpractice and be separated into various fractions such as normallygaseous hydrocarbons, gasoline constituents, gas oil, tar, coke and thelike as desired.

A temperature from about 750 F. to about 1800 F. and more preferably 800F. to 1300 F. is maintained within the reaction zone. The pressure isnot critical and may be atmospheric or a few pounds above atmospheric,in other words, sufficient to overcome pressure drops in the system. Theshale remains resident in the reaction zone for a sufficient period oftime to effect the desired conversion.

Accurate control of temperature is possible by use of heat-carrying gas,and the temperature in the pyrolysis zone is readily raised or lowered,depending upon the nature of the product desired, by merely increasingor decreasing the rate of flow of the heat-carrying gas or alternativelyby varying the temperature of the heatcarrying gas.

In all retorting operations, the time-controlling factor is the rate ofheat transmission to the shale particles. In the instant processresidence times as low as eight minutes may be used. Little is gained byincreasing the contact time past eight to ten minutes. This compareswith holdup times of 60 to 160 minutes in more conventional retorts.Charge rates as high as 500 to 1250 pounds of shale per hour per squarefoot of reactor cross-section are possible in the instant process.

It has been found that high oil yield is favored by decreasingtemperature and shale particle size; the space velocity function passesthrough a maximum oil yield value. Retorting rate is favorably affectedby increased space velocity and gas temperature, both of which tend toimprove heat transfer characteristics.

The use of vacuum retorting is within the scope of the present process.

While the preferred embodiment of my invention has been shown anddescribed, it will be understood that changes and modifications may bemade that lie within the skill of the art. Hence, I intend to be limitedonly by the appended claims.

I claim:

1. A process for producing oil and gas from a solid oil-bearingparticulate material which comprises delivering said material as freshfeed to a pyrolysis zone and pyrolyzing said material in the pyrolysiszone while rotating and milling said material with extraneousheatcarrying bodies having a particle size greater than the particlesize of said material, recovering a hydrocarbon overhead portion and aresidue portion separately from said zone while retaining said bodies insaid zone, introducing hot non-combustion supporting gas into thepyrolysis zone at a rate insufficient to suspend said bodies in the gas,contacting the gas with said bodies to heat said bodies bynon-combustion contact in situ in said zone, and maintaining the amountof heat introduced into said pyrolysis zone by said hot gas at a levelproviding the desired pyrolyzing temperature in said pyrolyzing zone.

2. The process of claim 1 wherein said maintaining step comprisesadjsuting the rate of flow of gas into the pyrolysis zone.

3. The process of claim 1 including the step of controlling thepyrolysis temperature by adjusting the temperature of the gas introducedinto the pyrolysis zone.

4. The process of claim 1 including the steps of fractionating saidoverhead portion to provide a hot light fraction, recycling at least aportion of said hot light fraction as said gas to said pyrolysis zone,and maintaining the rate of recycle suflicient to provide the properpyrolyzing temperature in said pyrolysis zone.

5. The process of claim 4 including the steps of burning at least partof said residue portion and passing said gas in indirect heat exchangewith the combustion gases from the burning step during the recyclingstep.

6. A process for producing oil and gas from a solid oil-bearingparticulate material which comprises delivering said material as freshfeed to a pyrolysis zone and flowing said material through said zone bygravity flow, pyrolyzing said material during its gravity flow throughthe pyrolysis zone while rotating said material with extraneousheat-carrying bodies having a particle size greater than the particlesize of said material, recovering a hydrocarbon overhead portion and aresidue portion separately from said zone while retaining said bodies insaid zone, debutanizing the hydrocarbon overhead to separate a hot lightbutanes fraction, recycling the hot butanes fraction as recycle gas tothe pyrolysis zone and introducing the recycled gas generallyhorizontally into the pyrolysis zone for contacting the recycle gas withsaid bodies and particulate material to heat said bodies and particulatematerial by non-combustion contact in situ in said zone, combusting therecovered residue to produce heat, transferring heat of combustion fromthe residue to the pyrolysis zone by flowing the recycle gas as a heattransfer medium in heat exchange with the combustion gases during saidrecycling step, controlling the amount of heat transferred by therecycle to said pyrolysis zone to maintain said zone at pyrolyzingtemperature, and passing the combustion gases from heat exchange withthe recycle gas into heat exchange with said fresh feed to preheat saidfeed.

7. A process for producing oil and gas from a solid oil-bearingparticulate material which comprises delivering said material as freshfeed to a preheater, delivering flue gas through said preheater forpreheating said material to a temperature below the pyrolysistemperature of said material, delivering the resulting preheatedmaterial from said preheater to a separate rotating pyrolysis zone,pyrolyzing said material in the pyrolysis zone while rotating andmilling said material with another heat-carrying material which suppliesheat for pyrolysis to said first material by intimate milling contacttherewith, recovering the results of said pyrolysis from said zone asproduct, providing a source of hot flue gas and transferring the heattherefrom to a portion of said product to provide a heat transfermedium, introducing the heat transfer medium into said pyrolysis zone indirect heat transfer contact with the materials therein to transfer heatto said materials while said first material is rotating and millingsubstantially in the absence of combustion-supporting gas andsubstantially in the absence of gaseous suspension of the heat-carryingmaterial in said zone to thereby supply the heat of pyrolysis by directnon-combustion contact in situ with the materials in said zone, andmaintaining the amount of heat introduced into said zone by saidheat-transfer medium at a level providing the desired pyrolyzingtemperature in said zone.

8. The process of claim 7 wherein said portion of said product is abutanes fraction of the pyrolysis vapors.

9. The process of claim 7 wherein the heat transferring step is byindirect heat exchange in the absence of combustion of the heatedportion.

References Cited UNITED STATES PATENTS 4/1931 Anderson 202218 11/1934Reed et a1. 201-12 8/1948 Lantz 201-37 11/1957 Lankford et al. 201-432/1962 Nevgns et al. 208-11 5/1962 Nea'ens 20811 10/1962 tis 2081111/1963 Natland 208-11 REIGN PATENTS 9/ 1954 Great Britain.

15 DANIEL E. WYMAN, Primary Examiner. PAUL E. KONOPKA, AssistantExaminer.

US. Cl. X.R.

